...cascade drop down? I'm not sure if this is my problem. I'm using CS3 Extended

I was trying to use Full screen mode, so all the drop down bar disappeared. Then when I wanted to Merge layers or use Filters, I pressed Alt+L (to call cascade drop down menu) or Alt+T (to call out Filter)...
but somehow ALL the buttons on the cascade are frozen...

I couldn't really use EVERYTHING until I switched back to the mode with task bar.

did I do something wrong?? I guess I might have done some very minor mistakes...

Help!! Thanks!!!